The structure of viruses and their organization
The structure of the virus is non-cellular, sincethey do not have any organelles. In a word, this is a transitional stage between dead and living matter. The viruses were discovered by the Russian biologist D.I. Ivanovsky in 1892 in the process of examining the mosaic disease of tobacco. The whole structure of the viruses is RNA or DNA encased in a protein envelope called the capsid. A virion is a formed infectious particle.
Influenza or herpes viruses have an additionalLipoprotein envelope, which arises from the cytoplasmic membrane of the host cell. Viruses are divided into DNA-containing and RNA-containing, because they can have only 1 type of nucleic acid. However, the overwhelming number of viruses are RNA-containing. Their genomes are single-stranded and double-stranded. The internal structure of the viruses allows them to multiply only in the cells of other organisms, and nothing else. They do not show any extracellular activity at all. The sizes of widespread viruses are from 20 to 300 nm in diameter.
The structure of bacteriophage viruses
Viruses that infect bacteria from the inside are called bacteriophages (phages). They are able to penetrate into the bacterial cell and destroy.
The body of the bacteriophage of E. coli has a head,from which comes a hollow core, wrapped in a sheath of contractile protein. At the end of this rod is a basal plate, on which 6 threads are fixed. Inside the head is a DNA molecule. With the help of special processes, the bacteriophage virus is attached to the body by bacteria of E. coli. Using a special enzyme, the phage dissolves the cell wall and penetrates the interior. Further, from the channel of the rod, due to the contractions of the head, a DNA molecule is squeezed out, and literally after 15 minutes the bacteriophage completely stops the metabolism of the bacterial cell to the desired mode. The bacterium stops synthesizing its DNA - it now synthesizes the nucleic acid of the virus. All this results in the appearance of about 200-1000 phage individuals, and the bacterial cell is destroyed. All bacteriophages are divided into virulent and moderate. The latter do not replicate in the bacterial cell, and the virulent form a generation of individuals in the already infected area.
Structure and activity of virusesis due to the fact that they are able to exist only in the cells of other organisms. Settled in any cell, the virus can cause a serious illness. Often, their attacks are exposed to agricultural plants and animals. These diseases dramatically worsen the fertility of crops and are the cause of the numerous deaths of animals.
There are viruses that can causevarious diseases and in humans. Everybody knows diseases such as smallpox, herpes, influenza, poliomyelitis, mumps, measles, jaundice and AIDS. All of them arise because of the activity of viruses. The structure of the smallpox virus almost does not differ from the structure of the herpes virus, as they are part of the same group - Herpes Virus, which includes some other types of viruses. In our time, the human immunodeficiency virus (HIV) is actively spreading. How to overcome it, while nobody knows.